Proteomic analysis of the rice seed for quality improvement

The amount, composition and distribution of seed storage proteins in rice are important factors for flavour and quality. We have analysed the seed proteomes of a relatively high-quality cultivar, 'Gopum' and a relatively low-quality cultivar, 'Dobong. By two-dimensional gel electrophoresis and subsequent MALDI-TOF/MS, we identified 'Gopum'- and 'Dobong'-specific seed proteins at 15 or 50 days after flowering. Of 53 identified proteins, we chose 15 that may have important roles in quality determination or maintenance through regulation of protein stability or disease resistance during grain filling and storage. By real-time (RT)-PCR, the expression of a few proteins tightly correlated with transcript levels at specific stages, while that of others did not. Our results suggest that levels of the identified proteins are determined post-transcriptionally or post-translationally, and that proteins which were expressed in the seeds of either 'Gopum' or 'Dobong' may affect rice flavour and quality.